OT: Current_Pending_Sector on /dev/sd?

hello,
I have a raid6 with 4 disks. 2 of them show Current_Pending_Sector 1.
The disks has warranty till Apr. 2019 so I decide to replace them.
After I change the disk and install it on an other computer to overwrite
with zero it the Current_Pending_Sector is gone.
What should I do? Whats our experience?
Best Regards,